There has been proposed an ultrasonic inspection device using an ultrasonic transducer composed of a plurality of piezoelectric vibrators that are formed independently from each other and arranged in a matrix (see, for example, Patent document 1). With the conventional ultrasonic inspection device, a layer structure having a plurality of different acoustic characteristics, and a defect, a void, and peeling in an inspection object having a curved surface can be visualized by using ultrasonic waves, but since judgment on the result imaged by the ultrasonic waves relies on eyes, it is difficult to automatically judge the result and to recognize the positional relation with the inspection object.
Such a conventional ultrasonic inspection device has the following problems.    [1] Objective and quantitative inspection is difficult since internal inspection relies on a person's observation of the imaged result.    [2] Brightness of an image varies at different depths of the inspection object due to the influence of a surface-reflected wave in the inspection object, the attenuation of the ultrasonic wave in the inspection object, and the like.    [3] Continuous imaging of a wide area is not possible due to the limited size of the ultrasonic transducer.    [4] If the periphery of an inspection area of the inspection object is uneven, the ultrasonic wave reflected on the uneven portion of the periphery deteriorates image quality of an internal image of the inspection object.    [5] It is not possible to automatically determine whether abnormality exists or not, based on position and shape information of the defect obtained from the three-dimensional imaging of the interior of the inspection object.
[Patent document 1] Japanese Patent Laid-open Application No. 2003-149213